The present invention relates to a molded plastic container or bucket and a compatible lid wherein the lid is removably secured to the open end of the container.
Many designs of molded plastic buckets or containers are known, for example, as disclosed in the following patents of John W. Von Holdt, Sr.: U.S. Pat. Nos. 4,375,948; 4,574,974; 4,512,494; 4,512,493; 4,452,382; 4,380,305; 4,308,970; and 4,210,258. Buckets or containers for food, paint, solvents and chemicals have been made from molded plastic materials in accord with the teachings of such patents. However, molded plastic buckets may lack the strength of buckets fabricated from metal. Thus special designs for plastic buckets may be adopted to obtain, for example, desired structural integrity, hoop strength and stacking strength. Hoop strength relates to the function or characteristic of the container to resist lateral deformation or change in the cross sectional shape of the container when lateral forces act upon the sides of the container. Stacking strength relates to the function or characteristic of the container to support vertical loads such as those which may occur when containers are stacked upon each other.
Also the design of the mouth or open end of a plastic bucket or container and a compatible lid presents a challenge to provide a lid that is properly retained and sealed on the open top of the bucket. Von Holdt in U.S. Pat. No. 5,538,154 entitled Snap-On Flexible Lid discloses a plastic lid with a peripheral flange constructed to enhance the xe2x80x9cdrop strengthxe2x80x9d of the lid while retaining flexibility adequate to permit removal of the lid from a container. Drop strength relates to the function or characteristic of the lid to maintain attachment to a container even when dropped from various heights. Von Holdt in U.S. Pat. No. 5,437,386 entitled Container with Tamper-Evident Lid Removal Means discloses additional embodiments of compatible molded plastic bucket and lid constructions.
Attachment of a lid to the open end of a molded plastic bucket often involves frictional or interference engagement or interaction between a rib, lip or groove molded in the open end of the bucket and a circumferential flange projection or groove in the lid. For example, the lid may include a radially, inwardly extending flange, rib or lip that is engaged with an outwardly extending rib on the outside wall of the bucket. A typical prior art lid and bucket combination is depicted in the cross section in FIG. 1. A bucket side wall 10 includes two circumferential, outwardly extending radial ribs 12, 14 which are each cooperative with a separate, inwardly extending circumferential, radial flange, 18, 20 on a skirt 13 of the lid 11. Flanges 18, 20 fit over the bucket ribs 12, 14 and thereby hold or retain the lid 11 on the bucket. The flanges 18, 20 resist release or removal of the lid 11 from the top or open end of the bucket.
Such prior art constructions work well. However, the need for a tamper resistant, improved lid construction for use in combination with a molded plastic bucket has remained.
In a principal aspect, the present invention comprises a molded plastic bucket or container and a compatible lid combination wherein the bucket includes at least two, radially outwardly extending, generally horizontal flanges or ribs at the top or open end of the bucket, and wherein the lid includes a depending skirt with at least two inwardly extending flanges or ribs that cooperate with the bucket ribs by engaging the bucket ribs. In this manner, the lid is held by cooperative engagement of the lid flanges with the bucket ribs. Further, the lid includes a downwardly extending, circumferential tongue adapted to fit in a circumferential groove in the top edge of the bucket. The profile of the inside of the depending skirt of the lid is shaped to thwart tampering with the seal of the lid on the container. A removable tear seal is also incorporated in skirt of the lid. The tear seal has a zigzag shape which enables removal of portions of the lower lid flange when the seal is removed.
Thus it is an object of the invention to provide an improved molded plastic bucket and lid combination.
A further object of the invention is to provide a molded plastic bucket with outwardly projecting lid retention ribs at the open end of the bucket and a lid with inwardly extending ribs or flanges that hook over the bucket ribs to thereby effect sealing and retention of the lid on the bucket.
Another object of the invention is to provide a bucket design and lid construction which is tamper resistant and which can be made from molded plastic.
Another object of the invention is to provide a molded plastic bucket and lid wherein multiple buckets each closed by a lid may be easily stacked.
A further object of the invention is to provide a combination molded plastic bucket and separable lid wherein the lid includes an improved seal.
Another object of the invention is to provide a combination plastic bucket and lid which incorporates multiple points of contact to effect a seal between the open end of the bucket and the lid.
A further object of the invention is to provide a bucket and lid made from molded plastic which is economical to manufacture, may be made for a reasonable cost of materials, and which has necessary structural integrity and strength, including hoop strength, stacking strength and drop strength.
These and other objects, advantages and features of the invention are set forth in the detailed description which follows.